Although atherosclerosis is a systemic disease, its manifestations are focal and eccentric, and each coronary obstruction progresses, regresses, or remains quiescent in an independent manner. The focal and independent nature of atherosclerosis cannot be due solely to the presence of systemic risk factors such as hyperlipidemia, diabetes mellitus, cigarette smoking, and hypertension. Local factors that create a unique local environment are a major determinant of the behavior of atherosclerosis in a susceptible individual.